The effect of growth hormone on pregnant or lactating sows has not been previously investigated. Nutritional treatments which increase fetal energy storage and/or elevate colostral fat percent have been demonstrated to improve the survival rate of "newborn" pigs Stahly et al., J. Anim, Sci., 1980, 51: 222 (Supplement 1); Boyd et al., J. Anim. Sci., 1978, 47: 883. Likewise, elevated milk production increases weaning weights of the piglets but present methods to accomplish this encompass only genetic selection. To date, published literature contains few studies with metabolic hormones on fetal energy storage or lactation effects in swine; but no reports exist for growth hormone.
Peel el al. J. Nutr., 1981, 111: 1662, describes the administration of bovine growth hormone to high yielding cows and demonstrated that at peak milk production, milk yield was enhanced by growth hormone. Milk production returned to normal levels following cessation of the treatment.
Machlin et al., J. Anim., 1972, 35: 794, Wassmuth, R. and H. Renter, Z. Tiersuchtg Zuchtgsbiol., 1973, 90: 56 and Chung et al., J. Anim. Sci., 1983, 57: 190 (Supplement 1) demonstrated that daily administration of growth hormone to older growing pigs improved daily gain and efficiency of feed utilization. The former demonstrated decreased fat content of the carcass.